15a Human Impact on Biodiversity - Health and Science ... · • Recovery from natural disasters • Food resources ... 8.Explain why biomagnification has a larger impact on organisms

The Human Impact and Biodiversity, HASPI Medical Biology Lab 15 411

Name(s): Period: Date:

Bioaccumulation: An Example of the Human Impact on Biodiversity HASPI Medical Biology Lab 15 Background/Introduction The Benefits of Biodiversity The variety of life on Earth is called biodiversity. Biodiversity is increased by the formation of new species (speciation) and decreased by the loss of species (extinction). An ecosystem or community with a large variety of species and relatively equal populations is considered to have high biodiversity, while either a low variety of species or unequal population sizes can cause an ecosystem or community to have low biodiversity. High biodiversity in an ecosystem means:

• Increased productivity • A greater variety of food sources • Increased sustainability for the species within the ecosystem • Better ability to withstand and recover from disasters

Why is biodiversity important? Each species in an ecosystem has an important role. Disruption or removal of a single species can cause a domino effect that impacts the entire ecosystem. For example, in 1969 the zoologist Robert T. Paine conducted a research study that involved removing a species of sea star, P. ochraceus, from a portion of Mukkaw Bay in Washington. The sea star primarily fed on mussels. The area contained 15 species at the start of the experiment, but over time only 8 species remained and the mussel population sky-rocketed, making up over 80% of the population of all organisms in the area.

In addition, a higher biodiversity can benefit humans. The following is only a short list of ways in which biodiversity can benefit us:

• Formation and protection of soil resources • Contributes to a relative stability in climate • Breakdown and absorption of pollution • Recycling and storage of nutrients • Ecosystem maintenance • Recovery from natural disasters • Food resources • Source of pharmaceuticals • Building products • Genetic diversity • Tourism and recreation • Cultural and aesthetic value

Anthropogenic Changes Humans depend on the living world for the resources and other benefits provided by biodiversity, but human activity is also having adverse impacts on biodiversity through overpopulation, overexploitation, habitat destruction, pollution, introduction of invasive

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species, and contribution to climate change. Thus sustaining biodiversity so that ecosystem functioning and productivity are maintained is essential to supporting and enhancing human life on Earth. Sustaining biodiversity also aids humanity by preserving landscapes of recreational or inspirational value. Moreover, anthropogenic changes (induced by human activity) in the environment—including habitat destruction, pollution, introduction of invasive species, overexploitation, and climate change—can disrupt an ecosystem and threaten the survival of some species, initiating the domino effect of impact.

Biomagnification & Bioaccumulation: An Example of Anthropogenic Change Pollutants that exist in small amounts in the environment (such as certain heavy metals and organic agents found in pesticides) become concentrated in organisms near the top of the food chain. In an estuary, for example, microorganisms called plankton absorb small amounts of pollutants such as PCBs (polychlorinated biphenyls); the fish that eat lots of plankton retain the pollutants in their tissues; then birds or people that eat the fish concentrate the pollutants in their own cells and tissues. This process is called biomagnification, and can eventually result in health issues when pollutant levels in the body become toxic. The actual building up of these pollutants in the body is called bioaccumulation.

Not all bioaccumulation is harmful. It is a normal and essential process for the growth of organisms. All animals bioaccumulate vital nutrients daily, such as vitamins, trace minerals, essential fats, and amino acids. What concerns toxicologists is the bioaccumulation of certain substances to levels in the body that cause harm. Some of the harmful substances that are capable of bioaccumulating include PCBs, fluoride, dioxins, boron, DDT (pesticides), and mercury. Where bioaccumulation occurs in the body depends on the substance. It could build up in a specific organ, such as the liver or kidneys. It could also build up in specific tissues, like fat, and every time fat is broken down in the body the toxin is released and makes the individual sick. The biggest health concern for these substances is that the body is not able to efficiently break down and/or remove them from the body. This causes them to build up over time and eventually reach toxic levels that can result in poisoning.

Substance

Cause Source for Human

Contamination

Symptoms

PCBs (polychlorinated

biphenyls)

Used as coolants and lubricants in transformers, capacitors, electrical equipment

Found in fish, surface soil, and drinking water

Stored in fatty tissues; liver damage, brain disorders, skin problems, cancer, hormone imbalance, birth defects

Dioxins

By-product of chlorine bleaching, burning plastics, pesticide production

Found in contaminated beef, pork, chicken, fish, milk, and eggs

Skin lesions, hormone imbalance, sterility, nervous system dysfunction, cancer

Mercury

Coal burning power plants (most common cause)

Found in seafood, especially tuna, shark, and swordfish

Neurological effects: tremors, blindness, numbness, pain, memory loss, seizures, death

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Mercury Poisoning: An Example of Bioaccumulation Ocean organisms ingest a form of mercury called methyl mercury. This pollutant is produced in several industrial processes and is found in run-off into streams and rivers. These rivers eventually lead to the ocean where the mercury builds up and is ingested by small organisms. Methyl mercury can cause sickness if inhaled, eaten, or placed on the skin for long periods of time. Usually mercury causes problems over years or decades, not immediately. In other words, being exposed to small amounts of mercury every day for years will likely cause symptoms that appear later.

Long-term exposure will likely cause neurological symptoms, including: • Numbness or pain in certain parts of the skin • Uncontrollable shaking or tremors • Inability to walk well • Blindness and double vision • Memory problems • Seizures and death (large exposures)

Medical evidence suggests that being exposed to large amounts of methyl mercury while pregnant can permanently damage the baby’s developing brain. Most doctors will recommend eating less fish—and avoiding shark and swordfish—while pregnant. These recommendations are made to be extremely cautious. Small and occasional exposures are unlikely to cause any problems. However, for anyone with a certain level of mercury found in the body, treatment of organic mercury exposure usually consists of medicines called chelators to remove it from the blood and draw it away from the brain and kidneys. Often, these medications will have to be used for weeks to months.

Review Questions – answer questions on a separate sheet of paper 1. What is biodiversity? 2. What is the difference between an ecosystem/community with high biodiversity

and low biodiversity? 3. What does high biodiversity mean for an ecosystem? 4. List 3 ways that biodiversity can benefit humans. 5. Explain one way that biodiversity directly benefits you. 6. What is anthropogenic change? Give 3 examples. 7. What is the difference between biomagnification and bioaccumulation? 8. Explain why biomagnification has a larger impact on organisms at the top of the

food chain. 9. What is one substance that can bioaccumulate? What is its cause, source, and

symptoms? 10.Explain how you personally could be exposed to mercury. How might you limit your

mercury intake?

http://dec.alaska.gov/eh/images/mercury/HgFishCycle.jpg



HASPI Medical Biology Lab 15 Scenario In this activity bioaccumulation will be modeled to demonstrate how a hazardous substance, such as mercury, can bioaccumulate in a food chain and eventually result in health issues for organisms at higher levels of the food chain. You will also have the opportunity to research methods to mitigate bioaccumulation of heavy metals within the environment, as well as organisms within the environment and the human body.

Materials 18 PROTIST vials 6 SMALL FISH vials Dialysis tubing 12 KRILL vials 1 HUMAN vial Tetra-ethyl lead solution 3 TUNA vials Beads – rep. mercury Cytoplasm solution Beaker Water Plastic pipette Timer Paper towels

Directions Part A. Modeling Bioaccumulation

Task Response This simulation will be done as a class! Wait to complete each step as your teacher instructs.

1

There are five different types of vials, each representing an organism in the food chain. • PROTISTS - producers located at the bottom of the

food chain. An example is plankton. • KRILL - shrimp-like organisms that feed on plankton. • SMALL FISH - feed on krill. • TUNA - feed on the small fish. • HUMANS - feed mostly on larger fish.

2 Obtain a vial from your teacher. You may not receive the same one as your neighbor.

3

Your organism is labeled on your container. The beads in the containers represent the mercury that the organism has consumed. All PROTIST vials contain beads. To start this activity, only the plankton that fed from the bottom levels have been contaminated with mercury. Mercury cannot be broken down so it remains in the organism and is passed to the next one that consumes it.

4 STAND UP if you were given a PROTIST or KRILL container.

5 Observe the PROTIST vials. How much mercury (number of beads) is present in each PROTIST vial?

Answer:

6

When directed by your teacher, students with KRILL vials will “consume” the PROTIST vials. (No rough play here; take caution not to spill the beads.) Pour the contents of the PROTIST vial into the vial of the KRILL that is consuming you. As soon as you have been consumed, return to your seat with your empty vial. KRILL should continue to consume until all PROTISTS are consumed.



7 STAND UP if you were given a KRILL or SMALL FISH container.

8 Observe the KRILL vials. How much mercury is present in each KRILL vial?

Answer:

9

When directed by your teacher, students with SMALL FISH vials will “consume” the KRILL vials. When consumed, pour the contents of the KRILL vial into the vial of the SMALL FISH that eats you. As soon as you are consumed, return to your seat with your empty vial.

10 STAND UP if you were given a SMALL FISH or TUNA container.

11 Observe the SMALL FISH vials. How much mercury is present in each SMALL FISH vial?

Answer:

12

When directed by your teacher, students with TUNA vials will “consume” the SMALL FISH vials. When consumed, pour the contents of the SMALL FISH vial into the vial of the TUNA that eats you. As soon as you are consumed, return to your seat with your empty vial.

13 STAND UP if you were given a TUNA or HUMAN container.

14 Observe the TUNA vials. How much mercury is present in each TUNA vial?

Answer:

15

When directed by your teacher, the student with the HUMAN vial will “consume” the TUNA vials. When consumed, pour the contents of the TUNA vial into the vial of the HUMAN that eats you. As soon as you are consumed, return to your seat with your empty vial.

16

Observe the HUMAN vial. Approximately how much mercury is present in the HUMAN vial?

Answer:

17

What is the difference between biomagnification and bioaccumulation?

Answer:

18

Compare the build-up of mercury in the protists up the chain to the human. Which organism do you think is affected more by mercury bioaccumulation? Explain your answer.

Answer:

19

Summarize how this simulation modeled bioaccumulation in a food chain.

Answer:

20

Draw the food chain represented by this simulation below.



Part B. Modeling Bioaccumulation in the Body: Tetra-Ethyl Lead Task Response

Specific organs and cells within the body tend to collect heavy metals and pollutants more than others. The liver and fat cells are particularly prone to bioaccumulation. In this portion of the activity, your lab team will create a model fat cell and observe the bioaccumulation of tetra-ethyl lead (the lead found in gasoline) in a fat cell.

1

Substances that are fat-soluble easily diffuse into fat cells within the body, where they remain until the fat cell is broken down to be used as energy. Tetra-ethyl lead is a heavy metal found in gasoline (primarily aviation) that is fat- soluble, and therefore bioaccumulates in fat cells. An individual can breathe in tetra-ethyl lead in airplane or car exhaust. When the body breaks down the fat cells containing tetra-ethyl lead, it also releases the tetra-ethyl lead, resulting in lead poisoning.

a. What does it mean if a substance is fat-soluble? b. What is tetra-ethyl lead, and how can it get into our bodies? c. Explain how the breaking down of fat cells for energy can result in lead poisoning within the body.

2 Fill a beaker with 150-250 ml of water.

3

Open the dialysis tubing by rubbing the two edges together. This is much easier if the tubing is wet! Tie a tight knot in one end of the dialysis tubing. You can do this by just tying a knot in the actual tubing, or by using string.

4

Using a plastic pipette, put approximately 10 ml of the “Cytoplasm Solution” into the dialysis tubing. The pipettes have a 1 ml mark on the side for measurement.

5 Tie off the other end of the dialysis tubing by tying a knot in the actual tubing, or using string.

6

The finished, enclosed dialysis tubing represents a fat cell. The fat cell is semi-permeable, and will allow water and fat-soluble substances, such as tetra-ethyl lead, to pass through the membrane.

a. What does the finished dialysis tubing represent?

7 Add 10 drops of the “Tetra-ethyl Lead Solution” to the water in your beaker.

Table 1. Contaminated Fat Cell Observation Time Observation 0 minute 2 minutes 4 minutes 6 minutes 8 minutes

10 minutes

8 Submerge the model fat cell (filled dialysis tube) into the beaker water.

9

Observe the fat cell over a 10-minute period. Record your observations of the fat cell every 2 minutes in Table 1.



10

Remove the fat cell from the beaker and dry it on a paper towel. You will notice the tetra-ethyl lead in the contaminated water has diffused into the fat cell by the brown to black color change of the cytoplasm.

a. What happened to the fat cell placed in an environment with tetra-ethyl lead? Hypothesize why this happened. b. Hypothesis: What will happen when the fat cell is removed from an environment with tetra-ethyl lead?

11 Empty the contents of the beaker down a sink. Rinse out and dry the beaker.

12 Fill a beaker with 150-250 ml of fresh water.

13

Since fat cells have a semi-permeable membrane, substances like water can diffuse through the membrane. Hypothesize what will happen when the fat cell is placed into fresh water, and is no longer surrounded by tetra-ethyl lead contamination.

14

Submerge the model fat cell (filled dialysis tubing) into the fresh beaker water.

Table 2. Fat Cell Observation Time Observation 0 minute 2 minutes 4 minutes 6 minutes 8 minutes

10 minutes

15

Observe the fat cell over a 10-minute period. Record your observations of the fat cell every 2 minutes in Table 2.

16

When the body needs energy from fat, it will break open fat cells. Using scissors, cut a hole in the dialysis tubing to represent the contents of the fat cell being released for energy. Leave the bag in the beaker of water. Observe what happens over 5 minutes, and record your observations at right.

a. What happened to the fat cell contaminated with tetra-ethyl lead when it was placed in a clean environment? Hypothesize why this happened. b. What happened over a 5-minute period when the fat cell (dialysis tubing) was split open?

17 Remove the dialysis tubing and discard it in the trash. Empty the remaining contents of the beaker down the sink.

18

Summarize what happened to the fat cell and tetra-ethyl lead throughout this simulation.

Answer:

19

Explain why bioaccumulation of substances, such as tetra-ethyl lead, in fat cells can result in poisoning.

Answer:

20

How did this simulation demonstrate bioaccumulation?

Answer:



Part C. Mitigating Bioaccumulation Task Response

Biomagnification and bioaccumulation of different substances can have a substantial impact on our environment and our health. Now that we have a better understanding of how this occurs, we need to look at how to mitigate, or reduce the severity and impact, of bioaccumulation. This part of the activity will give you the opportunity to research, design, evaluate, and refine a solution for reducing the impact of bioaccumulation on the environment, on biodiversity, and health.

1

Choose one of the following real-life bioaccumulation scenarios. Proceed through the engineering process steps below, using the Internet for research, and design a concept that could be used to mitigate bioaccumulation.

Scenarios: • Methyl-mercury • Cyanide • Ciguatoxin • Tetra-ethyl lead • Vitamin A and carnivores • Polychlorinated biphenyls (PCBs) • Dichlorodiphenyltrichloroethane (DDT)

Process: Define the Problem & Conduct Background Research

2 Use the Internet to research the substance you chose, and answer the following questions. You will need to specifically research the substance in reference to bioaccumulation and/or biomagnification. Cite your reference source(s) for each answer.

3

What is the substance, and what is its source?

Reference:

4

How does it get into the environment?

Reference:

5

Where can it bioaccumulate in the environment?

Reference:

6

Where can it bioaccumulate in an organism?

Reference:

• Polynuclear aromatic hydrocarbons (PAHs) • Zinc • Strontium-90 • Selenium • Copper • Cadmium • Chromium • Nickel



7

How does its bioaccumulation impact the health of the environment?

Reference:

8

How does its bioaccumulation impact the health of the organism?

Reference:

9

How can its bioaccumulation impact human health?

Reference:

Process: Brainstorm, Evaluate & Choose Solution 10

DO NOT RESEARCH THIS! Brainstorm three ideas, or designs, that could be used to mitigate, or reduce the bioaccumulation of this substance in the environment.

Idea 1: Idea 2: Idea 3:

11

Evaluate and rank each idea based on cost, safety, and reliability. Also, consider the social, cultural, and environmental impacts.

Idea 1 Idea 2 Idea 3

Approximate Cost

Safety

Reliability

Social, Cultural, or

Environmental Impact?



12

Choose one of the ideas to expand upon, and develop further.

a. Which idea did you choose and why?

Process: Develop & Test a Solution

13

What materials will you need to design your idea?

Materials:

14

What process or procedure will be needed to develop your solution?

Procedure:

15

Draw or describe a prototype version of your solution.

16

How will you test the effectiveness of your solution?



Connections & Applications Your instructor may assign or allow you to choose any of the following activities. As per NGSS/CCSS, these extensions allow students to explore outside activities recommended by the standards.

1. DIOXIN CONTAMINATION IN OUR FOOD SUPPLY: Dioxins are a common contaminant found throughout our food supply. Using the Internet and the graph below, answer the following questions:

a. What are dioxins, and how do they get into our food supply? b. How can we prevent dioxins from getting into our food supply? c. According to the graph below, what food source had the highest level of dioxin

contamination in 1995? Why do you think this was the case? d. According to the graph below, what food source had the lowest level of dioxin

contamination in 1995? e. According to the graph below, rank the following foods from lowest to highest

dioxin contamination: Chicken, eggs, beef, pork, fish, and milk. f. The abbreviation “ppm” stands for “parts per million” and “ppb” stands for

“parts per billion.” The abbreviated units for this graph are “ppt.” What does that stand for?

Levels of Dioxin in U.S. Food Supply (1995)

Chart from May 2001 study by Arnold Schecter et. al., Journal of Toxicology and Environmental Health, Part A, 63:1–18.



2. ANALYZING THE DATA: MERCURY LEVELS: Table A contains the average level of mercury in parts per million (ppm) found in two contaminated environments at each trophic level. Use the table to create a bar or line graph summarizing the information.

Table A. Mercury Levels (ppm)

Trophic Level Tested Environment A:

Pacific Ocean near California coastline

Environment B: Atlantic Ocean near New York coastline

Producers 1 ppm 2 ppm Herbivores 3 ppm 34 ppm Primary Consumers 9 ppm 56 ppm Secondary Consumers 22 ppm 112 ppm Tertiary Consumers 48 ppm 390 ppm

a. According to the graph you created, fish from which environment would be more risky to consume? Explain your answer.

b. The World Health Organization has put the level of risk for mercury poisoning at 50 ppm. Is anyone that is consuming fish caught from the California or New York coastline at risk of mercury poisoning? NOTE: The FDA does not allow fish with greater than 1 ppm to be sold to consumers, so don’t panic!

c. According to Figure A below, which U.S. states have the highest level of mercury in their water systems? Why do you think this could be? Explain your answer.

3. RESEARCH: ANTHROPOGENIC CHANGE: Anthropogenic changes (induced by human activity) in the environment can disrupt an ecosystem and threaten the survival of some species. Choose one of the following human activities: Habitat destruction, air pollution, water pollution, introduction of invasive species, overexploitation, or contribution to climate change. Conduct Internet research and answer the following:

a. How can this human activity impact the environment? Provide a description and summary of at least 3 real-world examples. (Cite your sources!)

b. How can this human activity impact our health? Provide a description and summary of at least 3 real-world examples. (Cite your sources!)

c. In what parts of the world does this human impact cause the most issues? Why? Explain your answer. (Cite your sources!)

d. How can this human impact be mitigated? Provide at least one example of how mitigation has already occurred. (Cite your sources!)

Figure A

http://www.usgs.gov/themes/factsheet/146-00/fig4b.gif



Resources & References • Extension Toxicology Network. 1993. A Pesticide Information Project of Cooperative Extension Offices of

Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. http://extoxnet.orst.edu/tibs/bioaccum.htm.

• Harris, W. 2013. What happens when a keystone species goes extinct? Conservation Issues, Environmental Science, How Stuff Works; http://science.howstuffworks.com/environmental/conservation/issues/keystone-species-extinct.htm.

• NIH. 2011. Mercury. U.S. National Library of Medicine, Article 002476.

http://www.nlm.nih.gov/medlineplus/ency/article/002476.htm.

• NRDA. 2008. What are PCBs? Wisconsin Department of Natural Resources. http://dnr.wi.gov/org/water/wm/foxriver/whatarepcbs.html.



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15a Human Impact on Biodiversity - Health and Science ... · • Recovery from natural disasters • Food resources ... 8.Explain why biomagnification has a larger impact on organisms